1. Field of the Invention
The present invention generally relates to transparent, multi-component, reinforced composite fibers that can be used to fabricate transparent reinforced composite articles such as lenses, windows, etc.
2. Description of the Prior Art
A common prior art technique of creating lightweight transparent articles, such as windows and lenses, involves forming a transparent polymer into the desired shape and size of the finished article using processing methods well known to the plastics industry. These processing methods include extrusion, injection molding of thermoplastic polymers, and casting reactive pre-polymer mixtures into molds and subsequent curing into polymers. The aforesaid processing methods result in transparent materials that exhibit the same bulk mechanical properties and performance of the polymer used to make them. Higher performance transparent polymer windows or lenses have been produced by laminating layers of different polymer films together, including laminations of films that have been stretched in one or two dimensions in order to increase the mechanical properties of the polymers being used, and thus increase the mechanical properties of the finished article. The disadvantages of these prior art approaches include limitations to the mechanical properties that can be attained using un-oriented polymers (i.e. extruded, injection molded, cast, etc.) and the limitations to the mechanical properties that can be attained in drawn polymer films. Another prior art technique for creating reinforced transparent articles entails using a glass particle or glass fiber reinforcing element in a polymer matrix wherein the glass and polymer are chosen to have identical or nearly identical indices of refraction to avoid scattering of light passing through the material. One disadvantage of using glass particles or glass fibers as reinforcement elements is the greater density of glass relative to polymers (typically two or three times greater) which results in a significantly heavier part when compared to the weight of a pure polymer article. Additional disadvantages of the aforementioned glass-reinforced approach to manufacturing transparent reinforced polymer articles are the difficulty in matching refractive indices of the various components, and the large difference in coefficients in thermal expansion (CTE) between glasses and polymers that can result in development of significant internal stresses in articles as the temperature changes. Another prior art technique to making reinforced transparent items is to use glass or ceramic as both the matrix and reinforcing filler. These glass/glass and glass/ceramic composites have significantly higher density than composites based on polymers, resulting in heavier finished articles.
What is needed is a new and improved transparent, reinforced composite that addresses the problems and disadvantages of the aforesaid prior art techniques.